The invention relates to a piston catcher for a pyrotechnic linear piston and cylinder drive on a belt pretensioner, wherein the cylinder has a frustoconical free end.
With the increase in the performance of belt pretensioner drives the piston catcher forming part of the linear piston and cylinder drive is becoming increasingly important. The piston catcher must in all cases be capable of preventing the piston shooting out through the open end of the cylinder, more particularly if the safety belt is not in use and at raised temperatures by which the performance of the pyrotechnic gas generator is made more effective. For this purpose it is necessary for the kinetic energy of the piston and of the parts driven by the same to be absorbed by plastic deformation of the frustoconically tapering free end of the cylinder. For such absorption of energy a range of axial movement must be designed for, which increases with the increase in the power of the pyrotechnic gas generator.